Many elongated medical devices are known that are inserted through an access pathway into a body vessel, organ or cavity to locate a therapeutic or diagnostic distal segment of the elongated medical device into alignment with an anatomic feature of interest. For example, catheters, introducers and guide sheaths of various types, drainage tubes, and cannulae are available that extend from outside the body through an access pathway to a site of interest and provide a lumen through which fluids, materials, or other elongated medical devices are introduced to the site or body fluids are drained or sampled from the site.
Such elongated medical devices must have flexibility to navigate the twists and turns of the access pathway, sufficient column strength in the proximal segment thereof to be pushed through the access pathway alone or over a guidewire or through a lumen, and the capability of orienting the distal segment and any electrodes or sensors or ports of the distal segment in a preferred alignment with an anatomical feature at the accessed site so that a diagnostic or therapeutic procedure can be completed. In general terms, the elongated medical device body must also resist kinking and be capable of being advanced through access pathways that twist and turn, sometimes abruptly at acute angles.
The distal segments of such elongated medical devices frequently need to be selectively deflected or bent and straightened again while being advanced within the patient to steer the catheter body distal end into a desired body lumen or chamber. Various steerable mechanisms have been disclosed to steer catheters and other elongated medical devices, e.g., steerable guidewires and stylets, that involving use of a deflection mechanism extending through a deflection lumen of the catheter body to an attachment point in the catheter body distal segment. Typically, elongated wires variously referred to as control lines or reins or deflection wires or traction wires or push-pull wires or pull wires (herein “deflection wires” unless otherwise specified), extending between a proximal control mechanism and the distal attachment point. More complex steerable catheters have two or more deflection lumens and deflection wires extending from the handle through the deflection wire lumens to different points along the length or about the circumference of the catheter body to induce bends in multiple segments of the catheter body and/or in different directions. The deflection lumens extend parallel to the central catheter body axis. In many cases, a handle is attached at the elongated catheter body proximal end, and the proximal end(s) of the deflection wire(s) is coupled to movable control(s) on the handle that the user manipulates to selectively deflect or straighten the distal segment and, in some cases, intermediate segments of the catheter body.
Many versions of electrophysiology (EP) catheters have been disclosed that are designed to perform mapping and/or ablation of cardiac tissue to diagnose and treat abnormal tissue that induces or sustains cardiac arrhythmias and that employ deflectable distal and intermediate segments controlled by deflection wire mechanisms. During an EP ablation or mapping procedure, the guide catheter must be maneuvered through a patient's branched vasculature to advance an EP device into a patient's coronary sinus. The steerable distal end of the guide catheter is used to orient the distal tip of the EP device with respect to tissue, such as a patient's endocardium, to facilitate proper delivery of the device's RF or ablation energy to the tissue. Highly complex shapes are sometimes found necessary to encircle a pulmonary vein orifice, for example, to ablate the left atrial wall tissue to interrupt arrhythmic pathways.
There remains a need for an ergonomic handle incorporating an effective and easy to use deflection mechanism.